The invention relates to an internal combustion diesel engine having a piston sliding in a cylinder and closed by a cylinder head forming the main combustion chamber. A pre-combustion chamber is arranged in the cylinder head and communicates by a connecting passage with the main combustion chamber, with a fuel injection nozzle and a glow plug arranged to project into the pre-combustion chamber.
In engines of this type, the injection and subsequent self-ignition of the injected fuel takes place in the pre-combustion chamber, which is designed in general as a turbulence chamber. The volume of the pre-combustion chamber is usually about 30-60% of the total compression volume of the main combustion chamber of the corresponding cylinder. Following the ignition of the fuel-air mixture in the pre-combustion chamber, the gas flame ignites through the connecting passage into the main chamber.
With the piston near top dead center, there is a very close spacing between the piston and the cylinder head, and the main combustion chamber is formed essentially by a trough-shaped recess incorporated into the face of the piston. The trough-shaped recess in the piston distributes the flame gases as uniformly as possible through the entire remaining portion of the main combustion chamber between the face of the piston and the cylinder head. This helps to assure extensive combustion of the entire mixture and a resulting high degree of efficiency of the diesel engine.
It has been found, however, that in turbulence-chamber diesel engines of this type, especially under full load conditions, a so-called black smoke developes as a result of incomplete combustion of the fuel, which it has hitherto been possible to reduce only by cutting down the quantity of fuel injected into the engine, which in turn dictates limiting the performance of the engine.